Production of succinimido-esters



Patented Apr. 3, 1951 UNITED STATES PATENT OFFICE 2,547,494 PRODUCTION OF SUCCINIMIDO-ESTERS Stanley P. Rowland, Philadelphia, Pa., assignor to Rohm & Haas Company, Philadelphia, Pa.,

a a corporation of Delaware N Drawing.

in which X represents an atom of oxygen or sulfur; in which the characters R R R R represent hydrogen atoms or monovalent, organic radicals which are unreactive with acid anhydrides, and therefore are free of alcoholic hydroxyl groups and primary or secondary amino groups, -NH2 and NH, and which preferably are hydrocarbon radicals; in which R also represents the same kind of monovalent, organic radicals as Rs but does not represent a hydrogen atom; and in which R R", R and R represent hydrogen atoms or hydrocarbon radicals, preferably'alkyl or alkenyl groups.

The process involves a new chemical reaction which comprises chemically combinin (a) succinic anhydride or a substituted succinic anhydride of the formula in which the HS and X have the significance described above. cording to the following general equation:

A specific ek'ample in which succinic anhydride,

This reaction takes place ac- Application December 17, 1949, Serial No. 133,675

per se, and a particular oxazoline, 2-heptadecenyl oxazoline, are reacted may make for a clearer understanding, at the outset, of the new reaction of this invention:

B- Succinimldoethyl oleate) Careful study has shown that the succinic anhydrides described herein react in the same manner as succinic anhydride per se, and that the thiazolines and other oxazolines described herein react in the same manner as the oxazoline above. That is, the groups which are represented by the nine Rs and X in the general formula given above remain intact and unchanged during the process, and the reaction does in fact take the course shown above. This process has such advantages over other methods of making imido esters, as speed and ease of reaction, quantitativene'ss and freedom from the formation of by-products.

The organic radicals which are represented by .Rs 9 must be unreactive with acid anhydrides. That is, they must be entirely free of of such substituents as hydroxy groups and amino hydrogen atoms which are capable 'of reacting with acid anhydrides, so that no interfering side-relations can take place. It is preferred that these radicals be hydrocarbon radicals such as alkyl,'ary1, alkaryl, aralkyl and cycloalkyl groups. The following list includes examples of such suitable, hydrocarbon radicals; methyl, ethyl, isopropyl, sec.-butyl, tert.-amyl, Z-ethylhexyl, lauryl, n-tetradecyl and octadecyl groups and the isomers of these groups; phenyl, tolyl, benzyl, p-octylphenyl, m-Xylyl, 2,4-ditert.-amyl phenyl; cyclohexyl; and naphthyl groups. In addition, the hydrocarbon group which is represented by R can be unsaturated. In fact a particularly valuable group of prodnets are those in which R is unsaturated. Such products have the added advantage of being more reactive and subject to oxidation and polymerization due to their unsaturation.

Although those reactants are preferred in which the substituents represented by the Rs are hydrocarbon radicals, it is a fact that succinimido esters are readily prepared from succinic anhydrides and oxazolines or thiazolines in which the substituents .Rs also contain other elements in additon to carbon and hydrogen. Such substituents however must be inert in the sense that they do not undergo reaction themselves with acid anhydrides. However, halogen groups, -Cl, Br and I, may be present on the -R-substituents as we l as nitro, NOz, ether, OR- keto, --C=O. aldehvdo, OHO, sulfonic, SOeI-I, carboxyl, COOH, or tertiary amino groups, NR2. None of these groups reacts with acid anhydrides and none interferes with the react on of the succinic anhydrides with the oxazolines or thiazolines.

The process of this invention gives rise to a large number of compounds, many of which were unknown h retofore. All of the compounds, however, fall within the class descr bed by the above general formula. A large class of operable oxazolines and thia olines are known and are shown in the literature. All of these react with succinic anhydrides to form succinimido esters by the methods set forth in the examples below. All that is required is to substitute an equ valent amount of one azoline: i. e. :an oxazoline'or a thiazoline, for the particular azolines shown in the examples. Thus in the same manner, the following azolines, of which the skeletal structureis 4 5 C-fl and in wh ch -Xis an oxy en atom in oxazolines or a sulfur atom in thiazoline's. combine in commolecular amounts wtih succinic anhydrides to form t e corresponding succ imido esters: 2- phenyl azolines; 2-o-tolvl azolines; *2-o-to yl azolines: 2-benzvlazolines': 2-'('o-. m-. an -n trophenyl): azolines; p-chlorobenzyl azolines; 2- undecyl 5-ch orcrnethyl azolin s; 2,4-dinbenyl azolines; 2,5-diphenvl azolires: 2-ph nvl-5-chloromethyl azolines; 2- (o-nitronhenyl) -5-ch oromethyl azolines; 2--(-p-nitrophenvl') 5 dieth-yl aminomethyl azolines: 2- (p-nitroohenyl) 5 dibutylaminomethyl azolnes: 2 phenyl 5.5: dimethy azolines; 2-p envl-5-oheny 5--methyl azolines; 2-(mand p-nitro h nyl)' 5'5-dimethyl azolines; 2- (aor B-na'ohth l) azol nes; 2-pmethoxyphenvl azolines; 2-o-ethoxvnhenvl azolines? Z-p-butvoxyphenvl az lines 2- (m nitro-pmethoxyphenyl) azolines; 2-(p-nitroohenyll-4- butyl azolines 2- (n nitrophenyl):-4-phenyl .azo

lines; 2=pheny-l-5-methyl azolines; .2-pheny1-5- ethyl azolines; '2-benzyl-5-mzthylazolines; 2- styryl-5-methyl azol nes; 2-(0- and p-tolvl)-5- methvl. azol nes; 2- (av and ,3-n-aphthyl).-5-methy1 azolines; 2-phenyl-4,5-dimethv-lazolines;; 2-(nnitrophenyl) -4.5-dimethyl azolines; 2-phenyl-4- methyl-5-ethyl azolines; 2,4'5-trimethy1 azolines; Z-undecyl 4,4 dimethyl azolines; 2 phenyl-4- methyl-4-ethyl azolines; 2-phenyl-4A-dimethyl azolines; 2-hentadecyl. azolines: 2-heptadecenyl azol n s; 2-hentadecyl4.4-dimethy1 azolines; 2- heptadecenyl-S-ethyl :azolines :v .2 -phenyl-4-methyl-5-phenyl azolines; 2'-methyl-4,5.5-tfiphenyl azolines; 2-phenyl-4-methy-l 5,5- dibenzyl azolines; 2-heptadecyl- 5 diethylaminomethyl azolines; 2-heptadecyl-5-ethyl azolines; vZ-heptadecenyl 4,5,5- trimethyl azolines; 2,4.5-triisobutyl azolines; 2,-heptadecyl 4,4,5,5 tetramethyl azolines; 2-methyl-4lsoamyl-4-methyl azolines; 2- heptadecy1-4-propyl 5 methyl azolines; Z-heptadecenyl-4,4-dimethyl-5-isopropyl azolines; 2-

hydrogen atoms, alkyl or alkenyl groups. On

the basis of cost and availability those succinic anhydrides which contain 1 or 2 alkyl groups on the same carbon atom are much preferred, although all of the alkyl-substituted succinic anhydrides are perfectly satisfactory from the standpoint of ease of reaction with the oxazolines and thiazolines.

The reactions between the succinic anhydrides and the azolines takes place fairly readily and often exothermically. Reaction takes place even at room temperature (20 C.) but the rate of reaction is unnecessarily slow. Heating of the reactants accelerates the rate of reaction and for this reason a minimum temperature of 50 C. is recommended. Temperatures up to 300 C. are operable but at the higher temperatures byproducts are freqvently formed, including polymeric materials especially when the group represented by R is unsaturated. Accordingly, an upper temperat re of 250 C. is much preferred. It is further advisable to employ lowertemperae tures when the azolioe contains two substituents on the 5-position than when the two substituents are both on the 4-position or on both the 4- and 5-positions. For convenience. inert solvents can be emploved. Likewise catalysts, such as alcoholates. zinc chloride and the like, can be u ed. altho gh ordinari y the reaction takes place rapidl eno gh i the absence of cata ysts. Other e pe' ie ts we l know to those skilled in the art. such as variations in pressure, solventextraction of the roduct, e cess f one reactant, particular y the azoline. and the like. can be used witho t departing from the spirit of this invention which is to prepare succioimido esters by reactin preferably under the influence of heat, eoguimolar amounts of a s ccinic anhydride and an o a' o ine or a thiazoline.

The following examples serve to illustrate the process of this invention.

EXAMPLE 1 Succinz'mz'doethyl acetate One-half mole each of succinic anhydride and.

2-methvl oxaline were mixed in a flask eoiunn d with a thermometer, a condenser and an a it tor. The mixture was heated to 175 C. and held at this te perat re for 2 ho rs. The reaction mixture was then fractionallv distilled at a reduced re sure of 2 mm. (H The main fraction, col ected at to 140 C.. was redistil'ed and the fraction boiling at '-134 C. and 2 mm. (H of pressure had an analysis correspondi g to that of succinimidoethvl acetate. Further ore. the product was identical with succinimidoethvl acetate which had been prepared b the acetylation of N-(fi-hydroxyethyl) succinimide.

EXAMPLE 2 Succz'nimidoisopropyl butyrate Eouimolar amounts of succinicanhydride and 72-propyl-5-methy1 oxazoline were mixed in a At the endof this The product was a clear distillable liquidl 'Its nitrogen-analysis (6.11%) corresponded to that of succinimidoisopropyl butyrate.

EXAMPLE 3 Succz'nimidoisopropyl pelargonate One-half mole each of 2-octy1-5-methyl oxazoline and succinic anhydride were heated, in a manner like that described in Example 2, for 2 hours at 190 C. The product was then fractionhally distilled under a pressure of 1 mm. (Hg). The main fraction, collected at 165 170 C., was

a a yellow oil. Its nitrogen-analysis corresponded 20 to that of succinimidoisopropyl pelargonate.

EXAMPLE 4 Succz'nimz'doisopropyl acetate By the procedure of Example 2, a mixture of one mole of succinic anhydride and 1.1 moles of 2-methyl-5-methyl oxazoline was heated for 2 hours at 135 C. A determination of the acid vnumber (95.4) showed that the reaction was 82.5% complete in this time.

The product was fractionally distilled and the fraction boiling at 130-140 C. and 2 mm. of pressure had a nitrogen-content which corresponded to that of sucl: cinimidoisopropyl acetate.

EXAMPLE 5 Succinimidoethyl oleate One mole of succinic anhydride and 1.1 moles of 2-(8-heptadecenyl)oxazoline was heated, according to the procedure described above, for 1.5 hours at 200 C. The acid number of the reaction mixture (53.7) indicated that 87% of the succinic anhydride had reacted. The product, succinimidoethyl oleate, was an oily liquid which distilled at 210-220 C. and 1.5 mm. of pressure.

EXAMPLE 6 HeptenyZsaccinimidoisopropyl iso'ualerate In the same manner, 0.1 mole of heptenylsuccinic anhydrid and 0.12 mole of 2-isobutyl-5- methyl oxazoline was heated for one hour at 238-251 C. The product was fractionally distilled under reduced pressure and there was obtained 22.9 grams (representing a 68% yield) of heptenylsuccinimidoisopropyl isovalerate which boiled at 1'75-185 C. and 2 mm. (Hg) of pressure. a It contained 4.0% nitrogen an analysis as against a calculated nitrogen-content of 4.15%.

EXAIVIPLE 7 (a,a-Dimethylbeneyl)-saccinimidoethyl acetate In a small sealed tube was reacted 0.01 mole of a-dimethylbenzylsuccinic anhydride,

0 cum-o (CH CHg and 0.011 mole of 2-ethyl oxazoline by heating at 160-1'75 C. for 1.5 hours. By the end of this period, the reaction-mixture had become very viscous. Titration of this product with standard no. Undeceny1succinic 2-Heptyl oxazoline Do 2 Methyl sue-cinic. Y Sucninic 1 alkali showed'that' 96.4%- of the anhydride had been converted to the imido-ester.

EXAMPLES 8-20 Extent of Anhydr Reaction Azoline Per cent Succimc 2-$.ll-Heptadecadienyl) oxazo- 88.5

Do 2,4.4-Trimethy1oxazoline Methyl succinic Z-lieptadecylfi-methyl exam- 1 a,fi-Dimethy1 succinic. 2-Propyl-i-ethyl oxazoline a,a-Dimethyl succinic do Succinic Z-Heptadecenyl-fiphcnyl oxazone. Do 2-Heptadecenyl-5-(p-chlorophenyl) oxazoline. 2-Heptadecyl-5-hexyl oxazoline..- 2-Heintyl-5-methyl thiazo1ine Do 2- lr-Nitrophenyl-5-ethyl oxazo- Do Z-p-Chlorophenyloxazoline eooocooo co P9 5 1" It'will be noted from the above examples that substituted succinic anhydrides react in the same way as succinic anhydride per se, and that the thiazolines and oxazolines also react alike. It is also true that the substituents on the anhydrides and azolines, which are represented by the Rs in the general formulas above, do not take part in the reaction and do not interfere with the reaction between the anhydrides and the azolines. Extensive study of the general process has shown that it is most advisable to employ lower temperatures of reaction when the azoline carries two substituents on the 5-position than when it carries two substituents on the 4-position or one each on the 1- and 5-positions or two on the 4- position and a third on the 5-position. When such a 5,5-disubstituted azoline is employed, it is suggested that the temperature be maintained below C.

The products of this invention have a wide variety of uses. Many of them have marked properties as regulants for plant growth. Others, especially those containing sulfur, are efiective as additives for lubricating oils. Still others, particularly thos which contain long hydrocarbon substituents, or a plurality of shorter hydrocarbon groups, are useful as plasticizers for synthetic plastics.

I claim:

1. A process for the preparation of B-succinimidoethyl esters of the general formula which comprises chemically reacting 1 at a 'temso it -.and anazoline of the general formula K 1 '0 1X l in which X is an atom from the class consisting of sulfur and oxygen; R ,'R R and R represent members .of; the class consisting of-.hydrogen atoms and alkyl, aryl, alkaryl, aralkyl, and :cycloalkyl groups; R represents a member of the class consisting of alkyl, aryl, aralkyl, alkaryl, and ,cyclohexyl groups and monounsaturated and diunsaturated aliphatic hydrocarbon groups containing not more than 17 carbon atoms; andR R", R and R represent members of the class consisting'of hydrogen atoms, alkyl groups and alkenyl groups.

2. A process for thepreparation of [i-succin- .imidoethyloleate which. comprises reacting at a temperature from 50 C. vto 250 C. equimolar amounts of succinic anhydride and '2-hepta decenyl oxazoline.

3. Aprocess for the preparationof-flssuccm- .imidoethyl linoleate which comprises reacting;at a temperature from C. to 250 C. :equimolar .amounts of succinic anhydride-and Z-heptadecadienyl oxazoline.

4. Aprocess for the preparation of -fi succinimidoethyl thiolinoleate which comprises'reacting at a temperature from 50 C. to 250 Ccequimolar amounts of succinic anhydride and 2-.heptadecadienyl thiazoline.

5. A process for the preparation of succinimidoisopropyl linoleate which comprises reacting at a temperature of 50 C. to 250 C. equimolar amounts of succinic anhydride and Z-heptadecadieny1-5-methyl oxazoline.

6. A process for the preparation of succinimidoethyl laurate which comprises reacting-at a temperature of 50 C. and 250 C. equimolar amounts of succinic anhydride and. 2-undeceny1 The following references are .ofrecord in the file of this patent:

UNITED STATES PATENTS Name Date Watt Sept. 16,11941 Cornwell Nov. 8, 1949 FOREIGN PATENTS Country 'Date Switzerland Jan. 16, 1931 Number Number 

1. A PROCESS FOR THE PREPARATION OF B-SUCCINIMIDOETHYL ESTERS OF THE GENERAL FORMULA 